LECTURES IN MICROBIOLOGY. Microbial Nutrition and Growth. Sofronio Agustin Professor. LESSON 5. Lesson 5 Topics. Microbial Nutrition Environmental Factors Microbial Growth. Microbial Nutrition. Based on intake: (a) Macronutrients (CHONPS) (b) Micronutrients (trace elements)
Microbial Nutrition and Growth
(a)Macronutrients (CHONPS) (b)Micronutrients (trace elements)
(a)Organicnutrients- contain carbon
(b)Inorganicnutrients- simple atom or molecule without carbon
Bacteria are composed of different elements and molecules, with water (70%) and proteins (15%) being the most abundant.
(e.g. sugar, proteins and lipids)
Summary of different nutritional categories of microbes based energy and carbon sources
A cube of sugar will diffuse from a concentrated area into a more dilute region, until an equilibrium is reached.
Facilitated Diffusion: The Process
Fate of cells in different osmotic conditions - isotonic, hypotonic, and hypertonic solutions
(Ex. Permeases and protein pumps transport sugars, amino acids, organic acids, phosphates and metal ions)
Example of permease, group translocation and endocytosis
20 to 40 °C
All are toxic byproducts of metabolism neutralized by enzymes SOD (superoxide dismutase), peroxidase and catalase.
SOD, peroxidase and catalase
Anaerobic culture techniques: (a) anaerobic chamber, (b) anaerobic jar
Thioglycollate broth is used to demonstrate aerotolerance of bacteria.
Aerobes, facultative anaerobes, and obligate anaerobes can be detected using this medium.
Ex: Campylobacter jejuni
Ex: S. pneumoniae
withstands hypertonic conditions
Ex. Halobacterium sp. (Archaea)
Ex. Staphylococcus aureus
Influence microorganisms have on other microbes:
Organisms that live together in close nutritional relationships
as a form of commensalism
Rod-shaped bacteria undergoing binary fission
Growth curve in a bacterial culture.
(b)Viable plate count
(d)Most probable number
(c)Dry weight determinations
Serially diluted samples are plated out and bacterial count expressed in CFU/ml.
Membrane filtration and coliform counts.
Turbidimetric measurements as indicators of bacterial growth.
The greater the turbidity the larger the population density.